EP0460643B1 - Sicherheitsschaltung für, zum Beispiel numerische Steuereinheit - Google Patents

Sicherheitsschaltung für, zum Beispiel numerische Steuereinheit Download PDF

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Publication number
EP0460643B1
EP0460643B1 EP91109197A EP91109197A EP0460643B1 EP 0460643 B1 EP0460643 B1 EP 0460643B1 EP 91109197 A EP91109197 A EP 91109197A EP 91109197 A EP91109197 A EP 91109197A EP 0460643 B1 EP0460643 B1 EP 0460643B1
Authority
EP
European Patent Office
Prior art keywords
circuit
signal
unit
emergency stop
clock signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91109197A
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English (en)
French (fr)
Other versions
EP0460643A3 (en
EP0460643A2 (de
Inventor
Hirohiko c/o MITSUBISHI DENKI K. K. Kazato
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Publication of EP0460643A2 publication Critical patent/EP0460643A2/de
Publication of EP0460643A3 publication Critical patent/EP0460643A3/en
Application granted granted Critical
Publication of EP0460643B1 publication Critical patent/EP0460643B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H1/00—Details of emergency protective circuit arrangements
    • H02H1/0061—Details of emergency protective circuit arrangements concerning transmission of signals
    • H02H1/0084—Details of emergency protective circuit arrangements concerning transmission of signals by means of pilot wires or a telephone network; watching of these wires
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/005—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for remote controlled apparatus; for lines connecting such apparatus

Definitions

  • the invention relates to a fault detection or alarm system for use with units which are connected by a signal cable, comprising a first unit, the first unit including an oscillator for generating a clock signal and a signal transmission circuit for transmitting the clock signal to the signal cable; and at least one second unit including signal determination circuit means connected to the signal cable for detecting when the clock signal is not included in the signal received from the cable and generating a fault signal in response to the absence of the clock signal.
  • fault detection or alarm system is capable of reliably performing a fault detection for emergency action such as the stoppage of a controlled device, despite loss of electrical communication or other problems. Also, it is of interest to use such a fault detection or alarm system in connection with a numerically controlled machine tool.
  • a fault detection or alarm system of the type specified above is known from the publication EP-A-0 066 737 where a two-wire circuit is provided comprising first and second lines which extend across detectors which may be provided as fire detectors.
  • the detectors are provided as shunts with respect to the two-wire circuit.
  • a monitoring shunt circuit is provided by means of which information is supplied to a control centre by sending monitoring pulses as signals that the two-wire circuit is continuously in order.
  • the detector is formed by detecting a shunt in which by means of a contact a resistor is shunted pulse-wise to the two-wire circuit.
  • the control of the respective contact is carried out by means of a pulse generator which in turn is controlled by a sensor.
  • the sensor starts the operation of the respective pulse generator if the sensor detects a fire.
  • the contact is actuated by pulses and thereby effects a pulse-wise increase of the closed-circuit current flowing through the two-wire circuit.
  • a closed-circuit current is mainly determined by the current consumption of the sensor connected in a shunt of the two-wire circuit and additionally by the current consumption of the monitoring shunt circuit.
  • This monitoring shunt circuit comprises a pulse generator which controls a contact which is connected to the two-wire circuit. As long as no interruption occurs in this two-wire circuit, the pulse generator of the monitoring shunt circuit is supplied with current and therefore permanently operates its contact in a pulsed manner.
  • the respective pulse generator is of the type which is programmed to output an individual pulse code.
  • the amplitude of the monitoring pulses supplied by the monitoring shunt circuit is considerably smaller than the amplitude of the pulse code supplied by the respective pulse generator associated with the respective sensor.
  • the control centre can evaluate both the monitoring pulses and the pulse codes of the respective sensor.
  • a first threshold trigger is provided which is adjusted that it switches through the detected value pulses received from the pulse generator of a sensor in the form of pulse codes, whereas it blocks the monitoring pulses generated by the pulse generator, using the signals of different amplitude.
  • a second threshold trigger is provided which has a considerably lower threshold value so that it switches through both the monitoring pulses and the detected value pulses.
  • the first threshold trigger switches through the pulses of the pulse code which are then evaluated in an evaluating circuit connected thereto and are converted into the display of an address in a display unit.
  • a numerical control unit includes a numerical operation section and a plurality of servo amplifiers provided for individual axes, which are connected by a signal cable. Signals transferred through this signal cable include command signals and emergency stop signals from the numerical operation section to the servo amplifiers, feedback signals from the servo amplifiers to the numerical operation section, and signals concerned with diagnostics and servo control adjustments.
  • Fig. 3 is a block circuit diagram of a known emergency stop device for a numerical control unit and an associated machine tool
  • Fig. 4 is a timing chart for the circuit diagram shown in Fig. 3.
  • the numeral 1 indicates a numerical operation section.
  • a fault detection circuit provided in the numerical operation section 1.
  • An emergency stop signal cable 3 is connected to the fault detection circuit 2, and servo amplifiers 4A to 4C are connected to the emergency stop signal cable 3.
  • Pull-up resistors 5 are provided in the servo amplifiers 4A to 4C and connected to the emergency stop signal cable 3.
  • Emergency stop circuits 6 are provided in each servo amplifier.
  • the fault detection circuit 2 in the numerical operation section 1 detects an emergency stop input from outside the numerical control unit in addition to internal faults within the unit.
  • the fault detection circuit 2 transmits a "low” signal to the emergency stop signal cable 3 when the operation is normal, and a "high” signal upon detection of any fault.
  • the emergency stop circuits 6 When the signal transmitted through the emergency stop signal cable 3 is "low", the emergency stop circuits 6 put the servo amplifiers 4A to 4C into a normal operation state as shown in Fig. 4. When that signal goes "high” at time tl, the emergency stop circuits 6 put the servo amplifiers 4A to 4C into an emergency stop state. That is, either the input of an external emergency stop command or the detection of any fault within the unit results in an emergency stop state.
  • Breakage of the emergency stop signal cable 3 itself is one of the failures which may occur.
  • the pull-up resistor 5 switches the input to the emergency stop circuit 6 to "high" to start the emergency stop state, thereby ensuring fail-safe operation.
  • the known circuit is designed to detect a signal transmitted from a fault detection circuit 2 through an emergency stop signal cable 3. Therefore, when the emergency stop signal is made "low” due to an accidental contact of the emergency stop signal cable 3 with a common or ground point or the like, or when there is a faulty circuit in any of the servo amplifiers 4A to 4C, the emergency stop state cannot be entered if an attempt is made to effect an emergency stop from the numerical operation section 1, and thus fail-safe operation cannot be achieved under such circumstances.
  • an object of the present invention to overcome the disadvantages in the prior art by providing a circuit which allows an emergency stop function to operate on a fail-safe basis even if a fault occurs in the emergency stop signal cable or in any of the controlled units.
  • the object underlying the present invention is solved by a fault detection or alarm system as specified above which is characterized in that the signal transmission circuit is arranged for operating on the clock signal from the oscillator and an output signal from a fault detection circuit located in the first unit and for transmitting the clock signal to the signal cable when the fault detection circuit does not detect any fault and for inhibiting transmission of the clock signal to the signal cable when the fault detection circuit detects a fault.
  • the signal determination circuit means include a first circuit for generating a signal in response to leading edges of the clock signal.
  • a specific embodiment of the system according to the invention includes a delay circuit coupled to an output of the first circuit and inverter means coupled to an output of the delay circuit.
  • the signal determination circuit means comprise a retriggerable stable multivibrator circuit.
  • a still further embodiment of the system according to the invention includes an emergency stop circuit for stopping the operation of the at least one second unit, coupled to an output of the signal determination circuit means.
  • the first unit comprises a control circuit for the at least one second unit.
  • the first unit comprises a numerical control unit and the at least one second unit comprises at least one servo amplifier.
  • the signal transmission circuit is an OR circuit combining the clock signal and the output of the fault detection circuit.
  • Fig. 1 is a block diagram of an embodiment of the present invention and Fig. 2 is a timing chart therefor, wherein parts similar to those in the prior art circuit are designated by the same reference characters.
  • the numeral 11 indicates an oscillator.
  • An OR circuit 12 is connected to the oscillator 11 and to a fault detection circuit 2.
  • These units 2, 11 and 12 constitute a signal detection circuit, the output side of which is connected to an emergency stop signal cable 3.
  • An edge detection circuit 13 is connected to the emergency stop signal cable 3 for generating a pulse upon receipt of a leading edge of an input signal.
  • a primary delay circuit 14 is connected to the edge detection circuit 13, and an inverting circuit 15 is connected to the primary delay circuit 14, the output side of which is connected to the emergency stop circuit 6.
  • the edge detection circuit 13, the primary delay circuit 14 and the inverting circuit 15 constitute a signal determination circuit.
  • the oscillator 11 continuously outputs a clock signal at predetermined intervals, both during normal operation and in an emergency stop state.
  • the output of the OR circuit 12 is a clock signal as shown in Fig. 2c.
  • This signal is input to the edge detection circuit 13 through the emergency stop signal cable 3.
  • the edge detection circuit 13 outputs a pulse as shown in Fig. 2d in accordance with the leading edge of the input signal.
  • the primary delay circuit 14 outputs that pulse input with an appropriate time constant, and if there is a pulse input, keeps the output "high” (see Fig. 2e).
  • This signal is inverted by the inverting circuit 15 and its output, i. e. the input of the emergency stop circuit 6, is set “low” as shown in Fig. 2f to cancel the emergency stop.
  • the OR circuit 12 employed as a signal detection circuit for synthesizing the emergency stop signal in the above embodiment may be replaced by a switch or a gate which has a similar function.
  • edge detection circuit 13, the primary delay circuit 14 and the inverting circuit 15 used as a signal determination circuit for determining the presence or absence of the clock signal may be replaced by a retriggerable stable multivibrator or the like to provide a similar facility.
  • the unbalanced connection type circuit for generating the emergency stop signal may be of a balanced type.
  • the present embodiment is applicable not only to the transmission of an electrical signal through the emergency stop signal cable 3 but also to the detection using an optical signal.
  • the determination made depending on whether the clock signal is present or absent is extremely significant.
  • the invention achieves an emergency fault detection/alarm circuit which interprets a transmitted signal to be an emergency stop signal when the signal transmitted does not include a clock signal. Therefore, when maintained “high” or “low” due to a signal cable or controlled element fault, the signal is interpreted as an emergency stop signal, allowing the emergency stop function to operate on a fail-safe basis.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Numerical Control (AREA)

Claims (8)

  1. Störungsdetektier- oder -warnsystem zur Verwendung mit Einheiten (1, 4A, 4B, 4C), die durch ein Signalkabel (3) miteinander verbunden sind, wobei das System folgendes aufweist:
    - eine erste Einheit (1), wobei die erste Einheit (1) einen Oszillator (11), um ein Taktsignal zu erzeugen, und eine Signalübertragungsschaltung (12) aufweist, um das Taktsignal zu dem Signalkabel (3) zu übertragen; und
    - wenigstens eine zweite Einheit (4A, 4B, 4C), die eine Signalbestimmungs-Schaltungseinrichtung (13, 14, 15) aufweist, die mit dem Signalkabel (3) verbunden ist, um zu detektieren, ob das Taktsignal in dem von dem Kabel (3) empfangenen Signal enthalten ist, und um ein Störsignal aufgrund der Abwesenheit des Taktsignals zu erzeugen,
    dadurch gekennzeichnet, daß die Signalübertragungsschaltung (12) dazu ausgebildet ist, eine Verarbeitung des Taktsignals von dem Oszillator (11) und eines Ausgangssignals einer Störungsdetektierschaltung (2), die in der ersten Einheit (1) angeordnet ist, vorzunehmen und das Taktsignal zu dem Signalkabel (3) zu übertragen, wenn die Störungsdetektierschaltung (2) keine Störung detektiert, und die Übertragung des Taktsignals zu dem Signalkabel (3) zu sperren, wenn die Störungsdetektierschaltung (2) einen Fehler detektiert.
  2. System nach Anspruch 1,
    wobei die Signalbestimmungs-Schaltungseinrichtung (13, 14, 15) eine erste Schaltung (13) aufweist, um ein Signal in Abhängigkeit von Vorderflanken des Taktsignals zu erzeugen.
  3. System nach Anspruch 2,
    das ferner eine Verzögerungsschaltung (14), die mit einem Ausgang der ersten Schaltung (13) gekoppelt ist, und eine Invertereinrichtung (15) aufweist, die mit einem Ausgang der Verzögerungsschaltung (14) gekoppelt ist.
  4. System nach einem der Ansprüche 1 bis 3,
    wobei die Signalbestimmungs-Schaltungseinrichtung (13, 14, 15) eine nachtriggerbare stabile Multivibratorschaltung aufweist.
  5. System nach einem der Ansprüche 1 bis 4,
    die ferner eine Not-Stopp-Schaltung (6) aufweist, um den Betrieb der wenigstens einen zweiten Einheit (4A, 4B, 4C), die mit einem Ausgang der Signalbestimmungs-Schaltungseinrichtung (13, 14, 15) gekoppelt ist, anzuhalten.
  6. System nach einem der Ansprüche 1 bis 5,
    wobei die erste Einheit (1) eine Steuereinheit (1) für die wenigstens eine zweite Einheit (4A, 4B, 4C) aufweist.
  7. System nach einem der Ansprüche 1 bis 6,
    wobei die erste Einheit (1) eine numerische Steuereinheit und die wenigstens eine zweite Einheit (4A, 4B, 4C) wenigstens einen Servoverstärker (4A, 4B, 4C) aufweist.
  8. System nach einem der Ansprüche 1 bis 7,
    wobei die Signalübertragungsschaltung (12) ein ODER-Glied ist, welches das Taktsignal und das Ausgangssignal der Störungsdetektierschaltung (2) verknüpft.
EP91109197A 1990-06-06 1991-06-05 Sicherheitsschaltung für, zum Beispiel numerische Steuereinheit Expired - Lifetime EP0460643B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2146176A JPH0439707A (ja) 1990-06-06 1990-06-06 数値制御装置の非常停止装置
JP146176/90 1990-06-06

Publications (3)

Publication Number Publication Date
EP0460643A2 EP0460643A2 (de) 1991-12-11
EP0460643A3 EP0460643A3 (en) 1992-10-21
EP0460643B1 true EP0460643B1 (de) 1996-04-17

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP91109197A Expired - Lifetime EP0460643B1 (de) 1990-06-06 1991-06-05 Sicherheitsschaltung für, zum Beispiel numerische Steuereinheit

Country Status (4)

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US (1) US5297149A (de)
EP (1) EP0460643B1 (de)
JP (1) JPH0439707A (de)
DE (1) DE69118749T2 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7015833B1 (en) * 2000-08-31 2006-03-21 Logitech Europe S.A. Multilink receiver for multiple cordless applications
AU2003224882A1 (en) * 2002-04-05 2003-10-27 The Trustees Of Columbia University In The City Of New York Robotic scrub nurse
JP3950832B2 (ja) * 2002-10-08 2007-08-01 ファナック株式会社 ロボット制御装置
JP2008234280A (ja) * 2007-03-20 2008-10-02 Matsushita Electric Ind Co Ltd 電子機器

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB921774A (de) * 1959-04-10
US4435698A (en) * 1980-06-11 1984-03-06 Hekatron Gmbh Circuit arrangement for the transmission of measurements to a central, especially in a fire alarm system
DE3122474A1 (de) * 1981-06-05 1982-12-23 Hekatron GmbH, 7811 Sulzburg "schaltungsanordnung zur uebertragung von messwerten, insbesondere in einem brandmeldesystem, zu einer zentrale"
US4521884A (en) * 1982-11-08 1985-06-04 International Business Machines Corporation Method and apparatus for error data feedback in a diskette drive
US4616335A (en) * 1983-06-30 1986-10-07 International Business Machines Corporation Apparatus for suspending a system clock when an initial error occurs
US4795921A (en) * 1984-04-23 1989-01-03 The Nippon Signal Co., Ltd. Logic operation-oscillation circuit
JPH0195306A (ja) * 1987-10-07 1989-04-13 Fanuc Ltd 非常停止制御回路
JPH01297974A (ja) * 1988-05-26 1989-12-01 Canon Inc 画像記録装置
US4916697A (en) * 1988-06-24 1990-04-10 International Business Machines Corporation Apparatus for partitioned clock stopping in response to classified processor errors

Also Published As

Publication number Publication date
EP0460643A3 (en) 1992-10-21
US5297149A (en) 1994-03-22
DE69118749D1 (de) 1996-05-23
JPH0439707A (ja) 1992-02-10
DE69118749T2 (de) 1996-12-05
EP0460643A2 (de) 1991-12-11

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